We propose to continue and extend our investigation of the molecular conformations and interactions of glycosaminoglycans and proteoglycans using X-ray diffraction analysis of oriented and polycrystalline fibers and computer-assisted modelling procedures. We expect to visualize the different kinds of intra- and inter-molecular contacts, including hydrogen bondings and cation and water bridges. The effects of three cation species Na ion, K ion, Ca2 ion will be considered particularly. Increased attention will be given to the iduronate-containing polymers, dermatan sulfates and the heparins.